Cord twister stopping means



ly 24, 1951 s. c. NELSON 2,561,749

CORD TWISTER STOPPING MEANS Filed Feb. 10, 1949 INVENTOR. SEDOON C. NELSON Patented July 24, 1951 UNITED STATES PATENT OFFICE American Viscose Corporationl Wilmington,

Del., a corporation of Delaware Application February 10, 1949, Serial No. 75,567

14 Claims. (01. 57-80) This invention relates to methods and apparatus for stopping strand-twisting machinery, particularly machinery in which two or more strands are twisted into the form of a plied or doubled construction.

In the operation of twisting machinery, particularly machinery in which two or more strands are twisted simultaneously to produce a cord, maintenance of the strands at uniform tension is highly important in order to produce a symmetrical cord. In the event of substantial variation in the tension, it is desired that the machine be stopped in order to remove the source of difficulty and thus prevent further mechanical trouble as well as inferior cord or thread. Various stopping devices sensitive to strand tensions are available as stopping means for twisting machines. Breakage of a single strand which does occur for this or any other reason is difficult to detect since twisting machinery on account of its closely built structure, is not equipped with breakage detection and stopping devices with respect to each strand, or devices which may detect a broken strand in the twisted cord. It is highly desirable, therefore, to be able to detect the breakage of a single strand in a cord or doubles twister so as to stop the machine and avoid the consequent loss of the strand, and the labor and time needed to bring the machine back into operation in such emergencies.

It is an object of the invention to provide means for stopping strand-twisting machinery operating within a desired tension range when the tension becomes either greater or less than the range.

It is another object of the invention to provide a means for stopping a multiple strand twister when a single strand breaks. Still another object is to provide a stopping device through which the cord or strand may pass while its tension varies within a range predetermined without producing fluctuations in the position of the device. An object also is to stop the twister spindle just before the strand runs entirely off of the supply package on the spindle so as to avoid relacing of the machine. It is also an object to provide a simple stopping device which may be readily installed on existing equipment. Other objects, features, and advantages will become obvious from the following description of the invention and the drawing illustrative thereof.

In the drawing,

Fig. 1 is a diagrammatic view of one embodiment of the invention;

Fig. 2 is a side view of apparatus illustrated in Fi Fig. 3 is a pictorial view of a modified stopping device; and

Fig. 4 is a pictorial view of still another modification.

According to the invention, a strand-handling machine may be stopped by passing the strand around an element of a device comprising a movable member supporting a pulley, said member having a neutral position permitting operation of the machine and being movable under the combined influence of the tension in the strand and the tension exerted by resilient members each of which control the movement of the memher in a distinct range of movement extending in opposite directions from the neutral position. The resilient members are so adjusted and set that movement of the member occurs only when the tension in the cord acting on the member exceeds or becomes less than that of a predetermined range. Deviation from the neutral position results in actuating a mechanism. for stopping the machine.

Figs. 1 and 2 illustrate a machine for forming a cord from two separate strands. A supply package 8 of one of the strands is supported concentrically about a twisting spindle l0; a supply package I2 for the other strand is supported independently of the spindle [0 on another portion of the twisting apparatus. The tail winding of the supply package l2 may be connected to the leading end of a reserve supply package l4 supported in close proximity thereto. A yarn strand I! from the supply package l2 passes through guides l5 and Hi to a tension device I8 supported above a cover l9 supported on a package holder 2| enclosing the package 8. A shroud 20 prevents the balloon 24 formed in the strand H from interfering with balloons of neighboring machines. After leaving the tension device, the strand passes through a thread guide 23 into a balloon 24 formed in the strand by a rapidly rotating flyer 26. After passing through the eye 21 of the fiyer, the strand enters a slot or bore 29 through the side of the spindle shaft [0 and passes downwardly through the hollow spindle shaft Ill.

The strand 30 passes from the package 8 upwardly into a tension device 32 supported above the package 8 in axial relationship with the spindle shaft l0 into which it passes. The tail end of the strand 30 stored in the package 8 (the last portion of package to leave the package holder 2|) is secured to a resilient anchor or spring fastened on the holder for a reason hereinafter explained. The device 32 is adjusted to impart approximately the same tension to the strand 30 as produced in the strand I! by the tension device I8. The strands l1 and 30 pass together in parallel untwisted arrangement from the slot 29 downwardly through the rapidly rotating shaft III to an idler roll 35 mounted on a bracket 85 extending from the spindle Ill. The axis of the roll is preferably at right anglesto that of the spindle. The parallel strandsll and 30 pass at least once around the roll 35 and then around a pulley 31 secured to the machinestopping device with which the invention is concerned. As the support 35 for the roll 35 is integral with or fixed to the shaft III, the roll 35 rotates on its own axis and turns with the spindle III on the axis of the spindle A twist is produced in the strand I! as it leaves the tension device l8; likewise a twist of similar direction and degree is imparted to the strand 38 as it passes from the tension device 32 into the top of the spindle shaft in. The twist imparted to the strands may be either 8 or Z depending on the direction or rotation of the flyer. However, the twist imparted to the strands while separated may be considered a false twist since the strands are twisted into cord in the opposite direction while passing between the roll 35 and the pulley 31. The resulting cord passing from the pulley 31 toward a withdrawal device 39 contains strands which are twisted about each other but in which the individual filaments have the same degree of twist with respect to the strand in which they occur as when they left the supply packages 8 and I2.

Device 33 pulls the strands, and the cord into which they are formed, through the twisting apparatus. It comprises two rolls 4| and 42 having axes canted with respect to each other to cause the thread to advance along their surfaces and to avoid friction or abrasive effects on the cord. The device 39 may be driven from a power takeoff 44 driven by the spindle shaft Ill. The power takeofl 44 may be employed also to drive a flyer 45 of a cord winding and twisting device 41 through a bevel gear drive 49.

A stopping device according to the invention may comprise the assembly shown in Fig. 1 including a lever 50 pivotably supported at 52 near one end; the pulleys 31 is rotatably mounted at the other end. The tension in the cord passing around the pulley urges the lever in a direction about the pivot 52 in opposition to tension springs tact with the strand (su ch as the pulley 31 mounted on the lever 50) is avoided regardless of fluctuations in the tension of the cord unless the tension in the strand goes below a, predetermined minimum or above a predetermined maximum. To obtain this result, the movement of lever 58 is controlled in a manner such that it moves only when the tension of the cord exceeds or falls short of the predetermined range for which the device I is set. In the embodiment just .described, the arrangement of the device is-such that when the desired range of tension variation in the cord is exceeded, the stronger spring 55 is extended by movement of the lever 50 while the spring 54 remains at constant length because of a tie-rod 62 in slip-connection with the levers 50 and 58 and exerts no additional effect in the operation of the device. When the tension in the cord drops below the operating tension range, the spring 55 isv held 54 and which control the action of the stopping device. The device as illustrated in Figs. 1

a lever 58, which pivots at 58, bears against or rests upon a stop or detent 53. This device is actuated only by large fluctuations in the tension of the cord which passes around the pulley 31. Examples of fluctuations of the severity required to operate the device are, the drop in tension produced when either or both of the strands l1 and 3|! break, andthe increase in tension produced when all of the strand 38 is withdrawn from the package 8, said increase in tension occurring when the transfer of the strand 33 through the machine is stopped by the tail end of the package being tied to the holder. By operation of the stopping device the twister is stopped until the package can be replaced. In the latter case, relacing of the twisting machine is avoided. Tension in the cord, if of sufficient magnitude, moves the lever 58 about the pivot at 52 in opposition to one or both of/the tension springs 54 and 55. The spring 55 is set or adjusted to greater tension than the spring 54. Movement of the lever to constant length by the engagement of detent 59 by the lever 53 and is therefore rendered ineffective. The spring 54 pulls the lever 50 downwardly when the cord tension is less than that of the desired operating range. The spring 54 is adjusted to a lesser strength or tension than the spring 55 to an extent which corresponds to the range of tension covering the normal variation in the tension of the cord through which it is desired that the stopping device he inactive.

The opposing forces, 1. e., the force originating in the cord and that produced by the springs 54 and 55, are applied to the lever at unequal distances from the fulcrum or pivot 52 of the lever 50. The opposing forces are therefore inversely proportional to the distances of their points of application from the pivot 52; and the mechanical moments which they produce about the pivot 50 are taken into account when providing the desired tensile or compression forces to be applied in opposition to cord tension to operate the device. Force originating in the spring 55 and producing a moment along the lever 53 is transmitted as a result of the connection of the spring 55 with the lever 58 and interconnection of the levers 50 and 58 by the extended spring 54 and the tie-rod 62 which share the forcebeing transmitted. The moments exerted on the lever 50 by the cord and springs 54 and 55 will be referred to in the following text rather than the actual magnitude of the forces moments.

When the moment of force applied to the lever 50 as the result of tension in the cord is greater than that exerted by the spring 55, the lever 53 tilts, the lever 58 is lifted from the stop or detent 59 by the link 52 and the spring 54, and the spring 55 is stretched. Meanwhile, the link 51 engages the button 64 of the switch 55 to stop the madesired for twister operation, the lever 58 remains at rest on the stop 58 because the moment produced by the spring is greater than that produced by the cord; meanwhile, of course,- the spring 54 is in the most extended condition permitted by the tie-rod 62 which limits the maxiproducing the guano mum rotation of the levers 58 and 58 from each other. When the cord tension falls below the desired operating range, as when one strand breaks, the spring 55, being adjusted to exert greater tension than the spring 54, holds the lever 58 against the stop while the spring 54 contracts and the lever 58 yields or swings toward lever 58 in accordance with the degree of lessening in the cord tension. As the lever 58 tilts, the link 56 actuates the switch 65.

The lower end of the spring 55 is secured to a fitting 55 adjustable with respect to the rod 51 secured to a stationary support 68. Likewise, the end of the spring 54 nearest the lever 50 is secured to a fitting 69 which may be adjusted with respect to a threaded rod extending through the lever 50. In this manner, the tensions of both springs may be adjusted to secure any limits desired to produce moments on the lever 50 which oppose a desired operating range of moments produced by the cord tension applied to the lever 58. For example, it may be desired to operate a machine to produce textile cord at an average cord tension of 1500 grams in a range between '1000 and 2000 grams. Assuming that the cord tension and the spring tension forces are applied at the same point on the lever to eliminate accounting for moments of the lever arms of various lengths and to simplify explanation, a spring 54 is adjusted so that when the tension in the cord drops below 1000 grams, the lever 58 is pulled downwardly in a counterclockwise direction from its normal operating position by the spring 54. The lever 58 although pulled upon by the spring 54, is held against the stop 58 by the stronger spring 55. When the cord tension exceeds 2000 grams, such as when the strand being withdrawn from the package is exhausted and the tail-end tied to the holder 2| produces a severe increase in the tension of the cord passing around the pulley 31, the lever 50 and the pulley 31 are pulled upwardly in opposition to the tension of the spring 55. Springs 54 and 55 therefore permit an operating tension range of 1000 grams corresponding to the difference in the strength or tension to which the two springs are adjusted or set. when twisting several strands to produce a cord, the weaker or less tense spring 54 should be preferably selected, so that the stopping device is operated by the reduction in cord tension which results when one strand breaks at any point along the path of the strand between the supply package to the take-up means for the twisted cord.

Fig. 3 illustrates a modified stopping device which may be used in place of the device described in the foregoing paragraphs. The cord is passed around the pulley 31 supported at the end of a lever which pivots at 11. As in the previously described device of Figs. 1 and 2, small links or rods 56 and 51 operate the microswitch 55. Rotary motion in a clockwise direction of the lever 15 is resisted by a plunger 18 urged toward the lever by a compression spring 88. The movement of the plunger 19 in a direction toward the lever is limited, however, by a nut 82 in threaded relationship with the threaded shank 8| of the plunger. The force required to move the plunger in opposition to the spring 88 may be varied by adjusting the position of a nut 84 relative to the plunger shank 8|. In the position illustrated by Fig. 3, the plunger 19 is in its most extended position from a bracket 86 in which It is supported. The lever 15 is shown in a normal operating position wherein it is held against the 8 head 85 of the plunger by tension in the cord passing around the pulley 31.

The clockwise movement of the lever 15 is also restrained by a tension spring 88 which extends from a threaded adjustable eye-fitting 89 secured to a portion of the frame 88 to the eye of a fitting 8| secured to a portion of the lever 15. A relatively large amount of compression is required to move the plunger head 85 toward the frame 85 against the spring 88 compared to the tensile force required to extend the spring 88. Both springs cooperate to restrain a clockwise or upward movement of the lever 15 as shown in Fig. 3. However, if the lever is moved in a counterclockwise direction from the position shown in Fig. 3, the plunger 15 remains in the position shown because of the nut 82 which acts as a stop, and the spring 88 contracts to pull the lever away from the plunger head 85.

For example, if the twister is operated with a normal or average tension exerted by' the cord on the pulley 31 of 1500 grams and it is wished to have the machine stop if the tension exceeds 2000 grams or becomes less than 1000 grams, the spring 88 may be selected and adjusted for a compressive strength which exerts a mechanical moment in the lever 15 with respect to the pivot 11 such that it produces 1000 position to the cord tension at the point at which cord tension is applied to the lever 15. Similarly, the spring 88 is selected and adjusted for a tensile strength which exerts such a moment on the lever that 1000 grams of force are produced in opposition to the cord tension at the point of its application. The pull of the spring 88 is applied continuously; the spring opposes the pull of the cord only when the lever is pulled by the cord in a clockwise direction from its neutral or usual operating position. Obviously, two springs 80 and 88 in unison provide a 2000 gram force opposing the movement of the lever 15 in a clockwise direction from the position shown whereas, only a 1000 gram pull by the spring 88 opposes movement of the lever in a counterclockwise direction as viewed in Fig. 3. The lever remains stationary until the force applied thereto from the cord exceeds 2000 grams, whereupon the lever moves counterclockwise to actuate the switch 55 by contact therewith of the lever 51. or, the force exerted on the pulley drops below 1000 grams causing the lever 15 to move in a counterclockwise direction and to move the element 56 lengthwise to operate the switch. By this arrangement the cord tension may vary between 1000 and 2000 grams without causing any movement in the lever 15 or otherwise actuating the machine-stopping device. The device of Fig. 3 responds to cord tension, and effects stopping of the machine, in the same manner as the earlier described modification of Figs. 1 and 2.

A further modification of the invention is illustrated in Fig. 4 having a switch 65, a pivotably supported lever 15, switch-actuating elements 56 and 51 and a pulley 31 similar to those 01 the previously described embodiments. However. in the device of Fig. 4, force applied to the lever 15 resulting from tension in the cord passing around the pulley 31is opposed by two compression springs 95 and 55. The springs urge the plungers 88 and 89 respectively in a direction substantially tangent to the arcuate path traversed by an element It! secured to the lever 15 to provide a surface for engaging the plungers.

The compression springs and 86 are selected according to the range of yarn tensions acceptgrams force in opable in operating a twister or other strandhandling machine. For example, if it is desired to operate the machine so that the cord tension may vary between 2000 and 1000 grams, the

cord tension which tends to pull the lever 15 out of its neutral position. The expansion of the spring 95 is not limited to the normal operating position of the lever 15. The spring 95 has a compressive strength such that it expands and moves the portion of the lever 15 to which the pulley 31 is attached downward when the cord tension drops below 1000 grams. Assuming for purposes of explanation that the moments of the cord tension and the spring tensions are applied at the same distance from the pivot axis of the lever 15, springs 95 and 96 are selected having strengths of 1000 grams each. Obviously, it takes 2000 grams of force to compress them simultaneously but as the plunger 99 cannot move beyond the position permitted by a stop-nut 103, the lever remains stationary in its normal operating position against the head of the plunger 99 between cord tensions'of 1000 and 2000 grams. When the tension falls below 1000 grams, the spring 95 expands, carrying the lever 15 downward to operate the stopping switch 65.

While the invention has been disclosed with respect to the doubling together of two yarns, it is applicable as well as to the doubling or combining of more than two yarns into a single cord. It may be used also in any single strand-handling machine. It is of particular utility, however, in connection with machines which handle two or more strands simultaneously since the springs of the device may be regulated in accordance with the reduction in the cord tension brought about by the breakage of a single strand. Moreover,

by fastening the tail-end of a supply package so that the end cannot be pulled through without tripping the stopping mechanism, laborious relacing of the twister is avoided.

In the specification, doubling is meant to include the folding or twisting of a singles and the twisting together of two or more individual strands and it is not intended to be restricted to the twisting together of two strands.

It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. A stopping device for a strand-handling machine comprising a controller for stopping the machine, a movable member having a path of movement of predetermined range connected with the controller, resilient means for controlling the movement of the member between an intermediate position along the range and one end thereof, and other resilient means of appreciably different tension for controlling the movement of the member between said position and the other end of the range.

2. A stopping device for a strand-handling machine comprising a movable member for actuating control means of the machine having a predetermined movement range in which an intermediate position of the member permits operation but out of which the member engages stopping means of the machine. resilient means engaging the member and controlling its movement between an intermediate position along the range and one end thereof, and second resilient means.

of appreciably different tension for controlling the member between said position and the other end of the range.

3. A stopping device for a strand-handling machine comprising a movable member for actuating control means of the machine having a range of movement along which there is an intermediate position of the member permitting operation of the machine, resilient means for engaging and controlling the movement of the member between an intermediate position .of the movement range and one end thereof at strand tension in excess of a desired tension range. detent means for limiting the deformation of the first resilient means to said portion of the movement range, and second resilient means adjusted and set to tension appreciably less than the first resilient means for controlling the movement of the member between said position and the other end of the movement range.

4. A stopping device for a machine for handling strands at tensions within a desired range comprising a movable member for actuating control means of the machine having a predetermined rangeof movement and having a portion adapted for passage of the strand therearound,

resilient means for controlling the movement between an intermediate position of the movement range and one end thereof at tensions greater "than the desired tension range, detent means for limiting the deformation of said first resilient means to said portion of the movement range, and second resilient means for controlling the movement of the member between said position and the other end of the movement range.

5. A stopping device for a strand-handling machine driven by an electrical means comprising a switch for controlling the flow of electrical power to the.machine, switch-actuating means in contact with the strand so as to be pulled in proportion to the tension in the strand, resilient means for engaging the actuating means at its operating position and resisting the movement of the actuating means in response to the pull of the strand and deforming to permit movement 1 of the actuating means only at strand tensions greater than a desired operating range, and second resilient means connected with the actuating means also resisting movement of the actuating means to a lesser extent such that deformation of the second resilient means occurs also at strand tensions less than the desired operating range.

6. A stopping device for a strand-handling machine driven by electrical means comprising a switch for controlling the flow of current to the drive means, a pivotable lever having its pivoting axis spaced with respect to the switch, means extending from portions of the lever spaced at opposite sides of the pivot axis to a region in close proximity of the switch whereby movement of the lever about the pivot axis from a neutral position will produce engagement of the means with the switch, and resilient means for holding the lever in the neutral position in opposition to the force exerted on the lever by a strand passing around a portion of the lever, said resilient means deformable only by movement of the lever produced by variations in the force exerted by the cord above or below a desired range.

7. A stopping device for a strand-handling machine driven by electrical means comprising a circuit-interrupting means for controlling the flow of electrical power to the machine, a pivottionary frame member spaced therefrom in the able support lever having its pivoting axis spaced direction from which the pull of the strand is with respect to the circuit-interrupting means, applied to the actuating means, detent means for elements -extending from the portions of the limiting the expansion of said compressible means lever spaced-at opposite sides of the pivot axis 5 to a degree corresponding to an intermediate toa region in close-proxlmityto the circuitposition of the actuating means which permits interrupting means whereby tilting of the lever operation of the machine, second resiliently comin either direction places either element into eni pressible means extending also in a direction to gagement with the circuit-interrupting means, }oppose the pull of the strand on the actuating a pulley rotatably attached near the end of the 101 means and having an expansion range beyond lever, resilient means connected to the lever and the intermediate position of the switch-actuating arranged to yield and permit movement of the means, said first and second compressiblemeans lever with respect to the pivotal axis in one direchaving such set and adjustment that in combination when a desired range of cordtension applied I tion they prevent movement 01' the activating to the lever at the pulley is exceeded, and secon 1 means from the hiterme iete po i n e c p h t resilient means attached to the lever for yieldproduced by ra d ens o s x e din a d ired ably resisting a force less than that of the desired range, and for strand tensions less than the range applied to the lever at the pulley and range, the second compressible means expands moving the lever about its ivotal axis in an o oand thereby moves the actuating means while site direction to the movement produced by the he fir t compre ibl means s Prevented m first-named resilient mea I expanding.

8. Astopping device for a'strand-handling ma- 11. A stopp ng device f r a Strand-handling chine driven by an electrical means comprising machine driven by an electrical means c p isa. switch for controlling the flow of electrical ing a switch for controlling the flow of electrical power to the machine, a switch-actuation means 26 power to the machine, a swit hc means in contact with the running strand responsive to n con ac wi h h r nnin s n and r vin a pull therefrom in proportion to the tension in a pull from the strand in proportion to the tenthe strand, resilient means connected with the sion therein, a l ver D v l pp e ar one actuating means and a, stationary anchqring end with its other rotatable toward the actuating point of such strength that it is extended only 30 m a tie-rod in s ip-conn o W h h a by movement of the actuating means from a. tile-ting means and the level which limits the neutral position resulting from tension in the maximum Spacing therebetween but Permits strand in excess of a desired range for operating wi n of portions of he ac u in m ans an the machine, and second resilient means of less the lever toward h h r and a detent f r strength than the first named resilient means for mit the w n f the l v aw fr m h moving the actuating means in an opposite direc- ,eetilating means, a Spring ccnnecting w eb tion from the neutral position when the tension portions of the actuating means n the lever. in strand falls below the desired operating range. and a o pr Substantially aligned With the 9. A stopping device for a strand-handling mafi st pr n e te d aw y m he lev i en chine driven by an electrical means comprising opposite direction and secured to astationary ana switch for controlling the flow of electrical o i eans. said second sprin adjusted and power to the machine, a switch-actuating means set o a e s n equa to t e null ex t d on it in contact with the running strand for receiving y the ,lever and the actuating means resul n a pull from the strand in proportion to th h from tension in the cord applied to the actuating sion therein, resiliently compressible means exmeans at the upper limit f a desired tension tending between the actuating means and a starange, nd s d fir t spr et and adjusted to a tionary frame member spaced from the side of ns on qual to the pull to which it is subjected the actuating means from which the pull of the y ra d tension ac n e a uat mea s strand is applied, detent means for limiting the a t e low r l mi f said ran e.

extension of the compressible means to an inter- A Stepping vi f r a r n -handling mediate position of th swit ht tin means machine driven by an electrical means compriswherein the switch is maintained in a closed ciring a s h or co trolli the ow or e ectrical cult position, and resiliently extensible means adpower to the machine, a lever piv l pp r .lusted and set to exert less force than the comat a poin e r One end ther of in spaced relapressible means extending between the actuating tionship wi h the Switch, m a f guiding a means and a stationary frame member spaced strand around another portion of the lever, l from the side of the actuating means opposite ments pivotally secured at points equi-distant on that of the compressible means, said compressible opposite sides of the pivot axis of the lever and and extensible means having such set and adextending toward a button f r Operating the lustment that in combination they prevent move- Switch, a ta ionary guide for supportin the element of the actuating means from an intermediments in alignment for engaging the button, 9. ate position except that produced by strand tensecond lever pi bly pp r at one d theresions greater than a desired range, and for strand of substantially parallel with the first lever, a tietensions less than therange the extensible means d in s p-co tion with sw n ab e po io s contracts and thereby moves the actuating means 0f e W l ver n l mi t n h while the compressible means is prevented from levers aw y om ch h r but not r r ct n expanding by the detent means. the rotation thereof toward each other, a spring 10. A stopping device for a strand-handling connecting swingable portions of the levers, a secmachinc driven by an'"electrica1 means com ris- 0nd spring extending away from the second lever 1118 a switch for controlling the flow of electrical n 8 direction op o that taken by the first power to the machine, a switch-actuating means p in and havin its other end secured to a stain contact with th running strand for receiving tionary anchoring means, said first spring set a pull from the strand in proportion to the tenand adjusted to a tension less than the pull sion therein, resiliently compressible means extransmitted to it through the first lever as a between theactuating means and a staresult 01 tension in the strand within a desired tension range for operating the machine, and the second spring set and adjusted to a tension such that it is extended only by a pull resulting from a strand tension greater than the desired operating strand tension range transmitted to it through the levers linked together by the tie-rod and the first spring.

13. A stopping device for a strand-handling machine driven by electrical means comprising a switch for controlling the flow of electrical power to the machine, a lever pivotably supported along a portion thereof, elements pivotably secured to the lever at points in opposite directions from the pivoting axis extending toward a button for operating the switch, guide means for bringing th elements into engagement therewith, means connected with another portion of the lever for guiding the strand and for translating the tension therein into a pull tending to move the lever about its axis, a stationary frame member spaced from the side of the lever from which the path of the strand extends, two parallel plungers passing through and supported by the frame member and engaging the lever, springs on each of the plungers for urging them toward the lever, detent means on one of the plungers for limiting its motion in response 'to the force imposed by the spring to an extent corresponding to the position of the lever in which neither element contacts the switch button, said springs having a combined strength which prevents the lever from moving and actuating the switch while subjected. to a pull resulting from strand tension in a desired operating range, and the spring of the unrestricted plunger of such adjustment and set that it remains compressed within the desired strand tension range .but expands to move the lever into switch-operating position if the strand tension falls below the range.

14. A stopping device for a strand-handling machine driven by an electrical means comprising a switch controlling the flow of electrical power to the machine, a lever pivotably supported along a portion thereof, elements pivotably secured to the lever at points spaced in opposite directions from the pivoting axis of the lever extending toward a button for operating the switch, means for guiding the elements into engagement with the button, means for guiding the strand about a portion of the lever along a path such that tension in the strand is translated into a pull tending to move the lever about its axis, a stationary frame member spaced with respect to the side of the lever approached by the strand path, a second frame member on the opposite side of the lever, a plunger extending through and slidably supported in the first frame member, a spring which resists compression for urging the plunger toward the lever, a detent means on the plunger limiting the movement of the plunger to a point corresponding to the normal operating position of the lever for maintaining a closed switch, a spring which resists extension extending between the lever in the second named frame member, the two springs being adjusted and set to exert such force as to prevent movement of the lever when subjected to a pull resulting from strand tension within a desired tension range and to permit movement when the strand tension is greater than this range, and the force exerted by the spring which resists tension being such as to contract the spring and to move the lever in the event that the strand tension falls below the desired range.

SEDDON C. NELSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,064,869 Zieve Dec. 22, 1936 2,425,977 Adams Aug. 19, 1947 

